Document GRE port options.

diff --git a/vswitchd/vswitch.xml b/vswitchd/vswitch.xml
index e1019e2d74349c4c0592d29566699417fec2252b..2aba34fdf4f1840d4db4c3635c2477586832893d 100644 (file)
--- a/vswitchd/vswitch.xml
+++ b/vswitchd/vswitch.xml
@@ -356,7 +356,88 @@
           <dt><code>tap</code></dt>
           <dd>A TUN/TAP device managed by Open vSwitch.</dd>
           <dt><code>gre</code></dt>
-          <dd>A GRE tunnel device managed by Open vSwitch.</dd>
+          <dd>An Ethernet over RFC 1702 Generic Routing Encapsulation over IPv4
+             tunnel.  Each tunnel must be uniquely identified by the
+             combination of <code>remote_ip</code>, <code>local_ip</code>, and
+             <code>in_key</code>.  Note that if two ports are defined that are
+             the same except one has an optional identifier and the other does
+             not, the more specific one is matched first.  <code>in_key</code>
+             is considered more specific than <code>local_ip</code> if a port
+             defines one and another port defines the other.  The arguments
+             are:
+            <dl>
+              <dt><code>remote_ip</code></dt>
+              <dd>Required.  The tunnel endpoint.</dd>
+            </dl>
+            <dl>
+              <dt><code>local_ip</code></dt>
+              <dd>Optional.  The destination IP that received packets must
+                match.  Default is to match all addresses.</dd>
+            </dl>
+            <dl>
+              <dt><code>in_key</code></dt>
+              <dd>Optional.  The GRE key that received packets must contain.
+                It may either be a 32-bit number (no key and a key of 0 are
+                treated as equivalent) or the word <code>flow</code>.  If
+                <code>flow</code> is specified then any key will be accepted
+                and the key will be placed in the <code>tun_id</code> field
+                for matching in the flow table.  The ovs-ofctl manual page
+                contains additional information about matching fields in
+                OpenFlow flows.  Default is no key.</dd>
+            </dl>
+            <dl>
+              <dt><code>out_key</code></dt>
+              <dd>Optional.  The GRE key to be set on outgoing packets.  It may
+                either be a 32-bit number or the word <code>flow</code>.  If
+                <code>flow</code> is specified then the key may be set using
+                the <code>set_tunnel</code> Nicira OpenFlow vendor extension (0
+                is used in the absense of an action).  The ovs-ofctl manual
+                page contains additional information about the Nicira OpenFlow
+                vendor extensions.  Default is no key.</dd>
+            </dl>
+            <dl>
+              <dt><code>key</code></dt>
+              <dd>Optional.  Shorthand to set <code>in_key</code> and
+                <code>out_key</code> at the same time.</dd>
+            </dl>
+            <dl>
+              <dt><code>tos</code></dt>
+              <dd>Optional.  The value of the ToS bits to be set on the
+                encapsulating packet.  It may also be the word
+                <code>inherit</code>, in which case the ToS will be copied from
+                the inner packet if it is IPv4 or IPv6 (otherwise it will be
+                0).  Note that the ECN fields are always inherited.  Default is
+                0.</dd>
+            </dl>
+            <dl>
+              <dt><code>ttl</code></dt>
+              <dd>Optional.  The TTL to be set on the encapsulating packet.
+                It may also be the word <code>inherit</code>, in which case the
+                TTL will be copied from the inner packet if it is IPv4 or IPv6
+                (otherwise it will be the system default, typically 64).
+                Default is the system default TTL.</dd>
+            </dl>
+            <dl>
+              <dt><code>csum</code></dt>
+              <dd>Optional.  Compute GRE checksums for outgoing packets and
+                require checksums for incoming packets.  Default is enabled,
+                set to <code>false</code> to disable.</dd>
+            </dl>
+            <dl>
+              <dt><code>pmtud</code></dt>
+              <dd>Optional.  Enable tunnel path MTU discovery.  If enabled
+                ``ICMP destination unreachable - fragmentation'' needed
+                messages will be generated for IPv4 packets with the DF bit set
+                and IPv6 packets above the minimum MTU if the packet size
+                exceeds the path MTU minus the size of the tunnel headers.  It
+                also forces the encapsulating packet DF bit to be set (it is
+                always set if the inner packet implies path MTU discovery).
+                Note that this option causes behavior that is typically
+                reserved for routers and therefore is not entirely in
+                compliance with the IEEE 802.1D specification for bridges.
+                Default is enabled, set to <code>false</code> to disable.</dd>
+            </dl>
+          </dd>
           <dt><code>patch</code></dt>
           <dd>A pair of virtual devices that act as a patch cable.  A 
             <code>peer</code> argument is required that indicates the name